This past Sunday, we had the great honor to host the Arlington Green Home Choice Program’s annual awards ceremony at OUR house! It was an awesome success. Arlington County uses this opportunity every year to recognize the home owners, builders and the homes that voluntarily participate in the program to build and retrofit homes to a high performing level that is “healthy, comfortable, cost efficient and reduces energy and water usage and protects the environment.” Helen, the manager of the Green Home Choice Program works tirelessly to engage builders through the entire process from design, construction to commissioning. She certainly kept us going through the hard times with her encouragement and her frequent site visits tell us how serious she and the county are about promoting green homes.

We really like the program because of its prerequisite that the home be Energy Star qualified. Even though Energy Star isn’t the most stringent standard out there, it is a great starting point and more importantly, it is performance based. This also means a Green Home Choice building will perform significantly better than a conventional home. Additionally, as Energy Star continues to tighten its standard, Green Home Choice homes will also improve in energy performance. Modeled after the EarthCraft program, Green Home Choice uses a score card to determine other sustainability features of a home, such as water use, site design, etc. Here’s the 72 page score sheet. http://freshaireva.us/wp-content/uploads/2012/01/Arlington-Green-Home-Choice-Guidance-Manual-1-01-12.pdf It’s also good to look for ideas in during the design process.

For this year (2011-2012), twelve homes were certified in the Arlington Green Home Choice program. Out of which 6 received”Certified”, 3 “Silver” and 3 “Gold” awards. This is the first year, Arlington has given out the “Gold” awards.

Special thanks to Helen Reinecke-Wilt, Joan Kelsch for organizing this successful event. To Jay Fisette for his support and commitment to a sustainable energy future. Congratulations to all the other Green Home Choice participants.

Stay tuned and be sure to come visit us on June 3rd for the 10th Annual Arlington Green Home and Garden Tour. For more information, click below.

Andy from Elysian Energy came out to do our final blower door test. We knew that we had a 1 ACH 50 from John’s test at the Meetup event with 30 people walking around and playing with the windows and doors. After taking some significant measures to air-sealing the windows and joints, Jim and Andy came for a second test which had a result that I thought was too good to be true but we felt comfortable enough to proceed with drywall and everything else. I think there was a discrepancy in how the total air volume was calculated…

Last Friday, Andy did our final testing the ACH at a number of different pressure levels and our final number was 0.52 ACH 50! The number is not 0.33 but we think it is a very respectable one for our first attempt at Passivhaus.

Final Blower Door Test

Air-tightness really is a difficult thing to achieve if you do not plan ahead. I think to get the air infiltration number even lower, air sealing must be done in conjunction with construction, i.e. tape as you build. I know of a builder that tapes up each nail hole right after the nail is hammered in so as to not miss any. It is obsessive but I am not sure if that effort is really excessive. Air-tightness is a quality of construction issue. We’ll never get to a 0 ACH 50 unless you build a house with a balloon but we can certainly get darn close…

The Importance of Air-Tight Construction

I know this is a huge topic but in an effort to share information and help me articulate the issue I must dip into the importance of air-tight construction. We had previously talked about this but we only talked about what we need to achieve but never explained why. Here are some of the “why”.

1. Energy conservation: Did you know that you can have all the insulation in the world and the build can still perform poorly? A leaky building envelope means “uncontrolled ventilation”. This means conditioned air can leak out and hot/cold air can leak in; thus decreasing the effectiveness of the insulation.

As you can see, air can leak in and out at a variety of places. This is “uncontrolled ventilation” or what some typical builders talk about when they say, “You don’t want a tight house, your house needs to breath.” Our retort is, “Your house does not need to breath, you do!”

2. Indoor Air Quality: Air can carry pollutants, moisture, odor and other undesirables into the building through these leaks. If you cannot tell where the air is leaking in from, you have no idea what pollutants are being carried into the indoor environment. As I like to say, “you are breathing like a frog.” I love Kermit the Frog but we are mammals, so let’s have a tight skin (air-tight building envelope) and breath through a dedicated respiratory system (an Energy Recovery Ventilator or Heat Recovery Ventilator) that brings in fresh air through a controlled path and filters it before we consume it.

Do you want to breath the air that passes through this window?

3. Vapor Penetration

Air carries a large amount of vapor or moisture. Each air leak has potential to cause water intrusion which in turn causes mold and structural damage if the moisture does not dry out. In well insulated buildings, this problem can get worse because there is so much material that can trap moisture. Therefore, air-tightness becomes even more important as building envelopes get tighter to keep water out in the first place.

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We placed an announcement on facebook to see how effective FB is at turning virtual connections to real life ones http://www.facebook.com/SouthernExposureHomes. In the end my fellow Passivhaus designer Bokyung and her husband Min and their lovely daughters came out to our green roof planting event.

Ready for planting!

Sedums

We have eight different varieties of Sedums, some are deciduous and some are evergreen. Some of them will disappear completely on the surface when winter comes and reemerge next spring. All of them flower and should be really beautiful in a couple of months.

Planting

Here’s Bokyung planting the Sedums.

All planted

All planted. It took eight of us (4 adults and 3 kids and 1 baby) about 2 hours to plant it all. It was a great time and now we can all say, “we’ve planted a green roof.”

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We started researching a way to build our green roof when we first conceived of putting a green roof on top of the garage. The foremost important thing to a green roof is to engineer it correctly to hold the loads. Since the green roof, once installed is not going to be removed, dead load considerations need to be discussed with the structural engineer so the resulting structure is strong enough for the green roof.

We opted to use a modular tray system for a number of reasons. First, the medium would be shallower which means lighter loads (about 3.4-4 inches). Second, a modular system is easily rearranged. Not that you would do this all the time, but it’s almost like rearranging furniture. Third, the perceived notion of fewer leakage concerns. Well, we think the less direct contact the roof membrane has to the growing medium which will carry moisture, the longer that roof membrane is going to last.

Additionally, for a membrane roof to last a long time, it needs to be properly slopped for drainage. Here’s Ruff Roofers installing tapered foam insulation that would create a slope to drain water into the scuppers.

Tapered Insulation

After that a TPO (Thermoplastic Polyolefin) is welded on top. This material is preferable to EPDM because it is largely a single sheet rather than strips and the seam strength is said to be 3-4 times stronger than an EPDM roof.

Here’s the TPO.

TPO Roof

We chose a white TPO to reduce solar heat gain and keep the garage and the membrane itself cooler. Additionally, to be extra cautious, Ruff Roofers added another sheet of TPO on top of the welded layer.

Then we started finalizing fun stuff on the roof.

Roof Layout

Our flat roof totals about 700 sqft, quite a large space to cover. We selected two things to install up there: Green Roof Trays and Decking Tiles. When we started out, both items are almost prohibitively expensive. However, I realized that more than half of the cost of the pre-planted green roof trays we had considered was shipping. I decided to find a local installer. However, the contractors that do this really charge an arm and an leg for it. We decided to see how much we can save by building our own green roof modules. After searching high and low, we came up with a solution which I think brings the price point low enough that almost anyone can do it.

Source Locally

The community of green roof professionals is a small one. This means everyone knows everyone and they’ve probably all been involved in projects together. It also makes it easier to find different components, you simply ask. We knew we needed the trays, the growing medium and the plants. We want to avoid paying for shipping because none of these parts are very expensive but shipping kills the budget.

After spending a few hours googling and reading green roof forums, I found greenroofoutfitters.com. Mike supplies both pre-planted trays as well as empty trays in South Carolina. Mike told me where I can pick up his empty modules about 1 hour away from me. Then I found Waynes Wholesale Nursery, a local supplier of green roof plants about 15 mins away in Fairfax. The growing medium took a lot longer, since dirt is the heaviest part, this is definitely not something we want to ship. After talking to people in about 5 different states in the region, someone pointed me to a supplier in Springfield Virginia that carries it. We were excited that it is actually just in our own backyard. So, now, we just need to put it all together. The total cost of the green roof system ended up being about 1/4 of the quotes we received. This also means we can now afford to build a larger green roof!

Picking up dirt

Eric laying out the trays and geo fabric

Growing medium

We had to move the growing medium one bucket at a time using a rope. Here’s Eric shoveling them. My back still aches.

Sedum

Wayne helped me select 8 different sedums that will work well for this site. Can’t wait to plant them.

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A few things got done since we last posted. Little by little this home will cross that finish line…

We finally installed the metal roof.

Metal Roof Installation

After a few spring rains throwing kinks into the schedule, Ruff Roofers was able to come and install the standing seam roof. We decided to use a metal roof for a few reasons. First, it should last almost forever. Second, if the homeowner chooses to add photovotaics onto the roof, they just need to clip them on instead of having to nail or screw the modules to the asphalt roof. We had Ruff Roofers add extra clips to make the metal roof extra secure in case solar panels are added at a later date.

Gutters

I really don’t like gutters. This is mainly because without gutters the facia just looks so much cleaner. Well, we do have a full basement so, we had to give in. At least Ruff Roofers did such a nice job with these half round gutters and the round downspout that I am even beginning to like the look.

Kitchen Cabinets arrived

Kitchen Cabinets

Thanks to Amicus Green Building Center, we were able to get our kitchen cabinets very quickly. These cabinets were manufactured locally (NC, I think), with no VOCs, formaldehyde, hazardous air pollutants, etc. They turned out beautifully.

Landscaping work also began outside.

Landscaping

Our friend, neighbor and landscape designer Scott Brinitzer’s landscaping team started the work of transforming this extremely well-compacted (nothing grows!) site into an amazing landscape. We can’t wait to seeing the results. We think it will knock your socks off!

Simple, when rain hits a regular roof, it flows where gravity takes it, taking with it, all the debris, nutrients, etc. with it and go into the storm drains and into the waterways it goes. When it hits a vegetative roof, it gets absorbed into the growing medium, the vegetation grows. A typical green roof system retains from 70-90% of every inch of rainfall and you don’t need to water the plants. It saves water.

2. Extends Roof Life: The green roof sits on top of the actual roof membrane, shielding the roof membrane from UV radiation and temperature swings, extending the life of the roof membrane by 2-4 times. It saves money.

3. Mitigates “Heat Island Effect”: When the sun hits buildings heat is retained making the surrounding space warm, then the heat re-radiates back when the surrounding space cools, basically, a negative thermal mass effect. When you have a green roof, it insulates the roof from the sun and through the evapotranspiration (cool word for plants sweating), it also cools the space surrounding the roof. It cools.

4. Green Space: Instead of a boring old deck, you get a garden! It Beautifies.

5. Reduce Heating and Cooling Loads: Essentially, you the green roof is insulation or as I like to call it, “outsulation”.

Here are a couple of cool ones:

Chicago City Hall

Photo courtesy of courtesy of DOE/NREL I Photographer: Katrin Scholz-Barth

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It’s been about 3 weeks since our last post. We’ve been working on interior finishes that seem to not want to be done. I guess this is sort of like when you cook a big dinner, 30 minutes before dinner, nothing looks done but you hope when it’s time to eat, everything comes out beautifully. WE HOPE…

Here are some of the tile work that LEON Home Improvement has done this week that we are very happy with.

Powder Room Pebble Tile

We think it has a very earthy character to it. Plus, you get a foot massage walking on it.

Master Bath Versailles Tile Pattern

This are Travertine tiles of various sizes arranged in a Versailles pattern. I think it turned out great.

Master Bath Tub

The tile is a large format ceramic tile that’s sparkly. The Rim is a Travertine mosaic, which Savador and his team had to painstakingly arrange by hand.